Cylindrical workpiece loading and feeding devices for centerless grinders

ABSTRACT

This invention relates to a device for the centerless loading, feeding and positioning cylindrical workpieces or workpieces of revolution in a centerless grinder, which comprises a vertical bearing surface against which the workpiece is urged laterally or axially, and a pair of radial bearing shoes disposed in proper angular relationship on a half-circumference above the horizontal axis of the workpiece of revolution, at least one of the shoes being responsive to the radial thrust of the grinding wheel, other elements being provided for feeding and positioning the workpieces, and also for ejecting the ground workpiece before another workpiece is fed to the grinding position.

United States Patent [191 Druge Apr. 30, 1974 [75] Inventor:

[73] Assignee: Societe Nouvelle De Roulements,

Annecy, France 22 Filed: May 23,1971

21] Appl. No.: 256,041

Gerard Druge, Annecy, France [30] Foreign Application Priority Data July 15, 1971 France 71.25837 [52] US. Cl. 51/103 WH, 51/215 H [51] Int. Cl 1324b 47/20 [58] Field of Search.... 51/103 Wl-l, 215 R, 215 CP, 51/215 H, 215 UE,105 R, 103 R 4/1953 Arms 51/103 Wl-l 12/1964 Lockwood 51/215 H X Primary Examiner-Donald G. Kelly Attorney, Agent, or Firm-Stevens, Davis, Miller &

Mosher [57] ABSTRACT This invention relates to a device for the centerless loading, feeding and positioning cylindrical workpieces or workpieces of revolution in a centerless grinder, which comprises a vertical bearing surface against which the workpiece is urged laterally or axially, and a pair of radial bearing shoes disposed in proper angular relationship on a half-circumference above the horizontal axis of the workpiece of revolution, at least one of the shoes being responsive to the radial thrust of the grinding wheel, other elements being provided for feeding and positioning the workpieces, and also for ejecting the ground workpiece before another workpiece is fed to the grinding position.

9 Claims, 3 Drawing Figures CYLINDRICAL WORKPIECE LOADING AND FEEDING DEVICES FOR CENTERLESS GRINDERS The present invention relates in general to means for feeding and positioning cylindrical workpieces to centerless grinding machines and has specific reference to an improved device of this character.

It is known to grind the outer peripheral surface or the bore of workpieces of revolution by using a device of the type disclosed in the US. Pat. application Ser.

No. 245,599 filed on Apr. 19, 1972, this last-named device comprising an axial rotatably driven bearing surface for the workpiece and a pair of lateral bearing shoes disposed angularly to each other, against which the workpiece is urged by disposing its center eccentrically in relation to the center of said bearing surface.

Now in actual service this arrangement is attended by several inconveniences. In fact, as the workpieces are fed and discharged during two separate successive steps, the operation can be regarded as an abnormally long one. The workpieces are fed directly by gravity; therefore, they are liable to be damaged on the shoes by striking them with an excessive force. On the other hand, the means necessary for carrying out this process vary as a function of the workpiece diameter and is therefore complicated, the same remark applying to the device itself as a whole.

Now the Applicant discovered that it was possible to avoid these inconveniences by using a device comprising an axial bearing surface and a pair of radial bearing shoes, but in the present instance these two shoes are disposed on a half-circumference lying above the workpiece axis. Thus, the workpiece is held not by gravity but only as a consequence of the eccentricity of the bearing surface with respect to the theoretical center of the workpiece. With this arrangement, relatively simple means can be used for handling the workpieces, such as an approach type feed system and gravity discharge means.

The invention will now be described with reference to two typical forms of embodiment given by way of example with reference to the accompanying drawing, in which: y I

FIG. 1 is a diagrammatic side elevational view showing a device for feeding and holding a workpiece of revolution to be ground internally;

FIG. 2 illustrates a similar device in the case of the peripheral grinding of a cylindrical workpiece, and

FIG. 3 illustrates on a larger scale a detail of a workpiece during the grinding of its bore.

Referring to FIG. 1, four workpieces of revolution 1, 2, 3 and 4 are shown at different successive stages of their bore-grinding operation. The workpiece 1 being ground on a centerless machine is held in the axial direction by magnetic attraction or mechanical pressure against a rotatably driven bearing vertical surface 18 here shown by its center S (FIGS. 1 and 3), the eccentricity of the workpiece center la relatively to the center S of said bearing surface being such that the rotation of the latter urges the workpiece in the radial direction against the pair of shoes 5, 6 disposed angularly to each other, for example perpendicularly, with their are fed by gravity along a trough 8. They are received separately by the V-shaped portion of a feed arm 9 rigid with the piston rod 10 of a fluid-operated cylinder 11. This arm 9 comprises an inclined side member 12 parallel to the cylinder axis, the successive workpieces being adapted to roll on this member 12 during the positive stroke of the feed arm 9 towards the shoes 5, 6. A control cranked lever 13 is fulcrumed about a pivot pin 14 and comprises an arm 15 having a roller follower l6 rotatably mounted to its free end; underlying the shoes 5, 6 is a hopper 17 for discharging the workpieces at the end of the grinding operation.

This device operates as follows:

Upon completion of the grinding operation proper the magnetic pull exerted on workpiece l, or the mechanical pressure urging this workpiece against its bearing surface, is discontinued. Pressure fluid is fed into cylinder 11 for extending same, whereby its V- shaped arm 9 moves towards the shoes until the next workpiece 2 engages the roller 16 and causes the cranked lever 13 to pivot about its fulcrum 14, so that its arm 13 moves the freshly ground workpiece 1 away from its bearing surface; thus, the workpiece 1 drops into the hopper 17. It may be pointed out that the magnetic pull or the mechanical pressure exerted on workpiece 1 for keeping same in engagement with the bearing surface is discontinued immediately when the desired grinding treatment is completed. Under these conditions, the slightest shock is sufficient for causing the workpiece l to fall into the hopper 17. Then the next workpiece 2 can move freely towards the shoes 5 and 6, the lever arm 13 resuming elastically its inital or inoperative position when the workpiece 2 separates from roller 16. As the workpiece 2 attains its grinding position the magnetic pull or mechanical pressure are restored, so that the workpiece is urged against the bearing surface and engages the shoes. At the same time, it separates from the V-shaped portion of arm 9 of piston rod 10. Meanwhile, the next workpiece 3 rolls along the inclined ramp l2 and is retained by the roller 16, until it nests into the hollow of the V-shaped portion of arm 9 as the latter resumes its retracted position. It is thus clear that the finished workpiece l is discharged and the next workpiece 2 is fed only during the positive stroke of piston rod 10. Thus the workpieces are retained in their grinding position by the magnetic or mechanical means only during the time necessary for the grinding operation proper. At the end of this operation the magnetic or mechanical action is discontinued, the workpiece 1 drops into the hopper l7 and is discharged to other handling means while the next workpiece 2 is positioned between the shoes.

The device illustrated in FIG. 2 is much similar to the preceding one. However, it departs therefrom in that it is intended for grinding the peripheral surfaces of workpieces 21 to 24 and therefore the shoes are set at an angle of about 12Qto each other. The workpieces delivered by the trough 28 are directed to the grinding position in contact with the shoes 25 and 26 and also with the grinding wheel 27 by the feed arm 29 rigid with the piston rod 30 of cylinder 31. To avoid an unduly long stroke of piston rod 30, the movement of its V-shaped extension 29 is obtained by causing the latter to bear through a roller 46 rigid therewith on an inclined cam face 47. The cylinder 31 is pivoted at its rear end of a pivot pin 45. During its truvel towards the shoes 25 and 26 the workpiece 22 engages the roller 36 carried by the arm 35 of control lever 33 and causes the latter to pivot about the fulcrum pin 34, so as to detach the workpiece 21 at the end of the grinding operation.

Of course, it is not compulsorily to discontinue the magnetic pull exerted on the workpiece during the discharge of this workpiece at the end of the grinding operation; however, if the magnetic pull were kept permanently it should not be too strong in order to avoid any interference with the action of lever 13, 33 as this would prevent the discharge of the ground workpiece.

In either forms of embodiment described herein it is contemplated that the ejection of the finished workpiece 1, 21 under the control of lever 13, 33 is caused by the pressure exerted by the next workpiece 2, 22 on roller 16, 36. Now it is obvious that the same control action could be obtained as well by utilizing for example the pressure exerted by the V-shaped piston-rod extension 9,'29 on said roller, the lever 13, 33 resuming its initial position immediately after the discharge of the ground workpiece to avoid any shock with the next workpiece being ground.

As shown in FIG. 3, the workpiece 1 of which the bore is to be ground is machined by a grinding wheel 7 urged in the direction B or C, the wheel 7 and the workpiece revolving in the directions shown by the arrows.

Of course, various modifications and changes may be brought to the specific forms of embodiment of the invention shown and described herein by way of example, without departing from the basic principles of the invention as set forth in the appended claims, as will readily occur to those conversant with the art.

What is clamed as new is:

1. A device for feeding and positioning workpieces of revolution in a centerless grinding maching, which comprises a bearing surface rotatably driven about its center and axially engaged by the workpiece, a pair of radial bearing shoes each having a-bearing mid-point which are disposed angularly to each other and against which the workpiece is urged by disposing its center eccentrically in relation to the center of said bearing surface, and a grinding wheel adapted to exert a radial pressure against at least one of said shoes, wherein the bearing mid-point of said shoes is provided on a halfcircumference overlying the horizontal axis of said workpiece, and wherein means are provided for feeding and positioning the workpieces towards said bearing surface, these means being disposed out of a gravity discharge path of the workpieces.

2. Device according to claim 1, characterised in that the workpiece feed means comprise an inclined trough.

3. Device according to claim 1, characterised in that the workpiece positioning means comprise a feed arm responsive to a fluid-actuated cylinder.

4. Device according to claim 3, wherein a V-shaped loading member is adapted to bring the workpiece in close proximity of the shoes and wherein said bearing surface has means to move the proximately located workpiece against said bearing surface in the axial direction.

5. Device according to claim 1, wherein said bearing surface has magnetic means to urge the workpiece against said bearing surface by exerting a magnetic pull thereon.

6. Device according to claim 1, wherein said bearing surface. has mechanical means to urge the workpiece against said bearing surface by exerting a mechanical pressure thereon.

7. Device according to claim 6, further comprising a control lever to eject the finished, ground workpiece which is activated by the movement of the next workpiece during the feed stroke thereof.

8. Device according to claim 5, further comprising a control lever to eject the finished, ground workpiece which is activated by the movement of a V-shaped loading member during the feed stroke thereof.

9. Device according to claim 6, further comprising a control lever to eject the finished, ground workpiece which is activated by the movement of a V-shaped loading member during the feed stroke thereof.

UNI'IED STATES PATENT OFFICE CER'IIFICA'IE OF CORRECTION ln ent fl Gerard Druge It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Heading:

Please correct the filing date of the application as follows:

Line 22 change "May 23, 1971" to May 23, 1972 Signed and sealed this 17th day of September 1974,

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer 7 Commissioner of Patents FORM PO-10SO (10-69) USCOMM-DC eoaveh ee u 5 GQVERNME'" R NYING OFFICE: Ian mass-334, 

1. A device for feeding and positioning workpieces of revolution in a centerless grinding maching, which comprises a bearing surface rotatably driven about its center and axially engaged by the workpiece, a pair of radial bearing shoes each having a bearing mid-point which are disposed angularly to each other and against which the workpiece is urged by disposing its center eccentrically in relation to the center of said bearing surface, and a grinding wheel adapted to exert a radial pressure against at least one of said shoes, wherein the bearing mid-point of said shoes is provided on a half-circumference overlying the horizontal axis of said workpiece, and wherein means are provided for feeding and positioning the workpieces towards said bearing surface, these means being disposed out of a gravity discharge path of the workpieces.
 2. Device according to claim 1, characterised in that the workpiece feed means comprise an inclined trough.
 3. Device according to claim 1, characterised in that the workpiece positioning means comprise a feed arm responsive to a fluid-actuated cylinder.
 4. Device according to claim 3, wherein a V-shaped loading member is adapted to bring the workpiece in close proximity of the shoes and wherein said bearing surface has means to move the proximately located workpiece against said bearing surface in the axial direction.
 5. Device according to claim 1, wherein said bearing surface has magnetic means to urge the workpiece against said bearing surface by exerting a magnetic pull thereon.
 6. Device according to claim 1, wherein said bearing surface has mechanical means to urge the workpiece against said bearing surface by exerting a mechanical pressure thereon.
 7. Device according to claim 6, further comprising a control lever to eject the finished, ground workpiece which is activated by the movement of the next workpiece during the feed stroke thereof.
 8. Device according to claim 5, further comprising a control lever to eject the finished, ground workpiece which is activated by the movement of a V-shaped loading member during the feed stroke thereof.
 9. Device according to claim 6, Further comprising a control lever to eject the finished, ground workpiece which is activated by the movement of a V-shaped loading member during the feed stroke thereof. 